Electric switch



K. c. ALLlsoN ELEC Filed sept. 23, 193e TRIC SWITCH V35/f .if

3 Sheets-Sheet 1 fff i,

I @MQW April 9, 1940 K. c. ALLISON 2,196,433

ELECTRIG SWITCH l Filed Sept. 23, 19158 3 Sheets-Sheet 2 'III l l'/////////| aff/yf.

K. C. ALLISON ELECTRIC SWITCH April 9, 1940.

Filed Sept. 23. 1958 3 Sheets-Sheet 3 y 7e 70 /T 725:9

Patented Apr. 9, 1940 UNITED STATES ELECTRIC SWITCH Kenneth C. Allison,

signor to Oak Manufacturing Company,

Arlington Heights, Ill., as-

Chi-

cago, Ill., a corporation of Illinois Application September 23, 1938, Serial No. 231,399

13 Claiml.

This invention relates to electric switches and particularly to switches wherein the movable portions may freely adjust themselves with reference to the contact requirements and thus eliminate or reduce strains upon the contacts themselves. In particular, the construction hereinafter disclosed has resulted because of a demand for an electric switch having greater flexibility and adaptability both in the number of circuits to be controlled and in the mechanical .action of the various parts. Thus, in radio receivers it is particularly desirable to provide a multiple switch operated by push buttons to change a large number of circuits with a view to selecting various wave lengths and wave bands. Because of the requirements for space, such a switch must have a large number of contacts compactly disposed.

In a switch as described above, it is desirable to have considerable play in the various parts in order to permit ready adaptation of the various parts to each other. However, the very existence of such play creates a problem in connection with the contacts. Inasmuch as each set of cooperating contacts includes a spring member, it is desirable to protect such spring member against distortion and abuse during the play of the various mechanical parts. This is attained in a simple and effective manner as will appear later.

In its more general aspect, the invention contemplates a pair of supporting members having opposed faces, normally in spaced parallel planes. From each face extend one or more contacts toward the opposing face or surface and between the free edge oi each contact and its opposing surface there is normally a clearance. 'I'he two supporting members are movable relatively lto each other and are adapted to have a permissible play except in the direction of switch motion. By adjusting the relative clearances, it is possible to have rigid contacts act as stop members during the play action and thus protect the delicate spring contacts against injury. lThe mechanical structure embodying this invention may assume various forms.

'I'he entire switch mechanism as hereinafter described is composed of a plurality of electrically separate switch sections. By virtue of the disposition of the stationary contacts on the supporting member, a large number of contacts may be disposed in compact array without enfdangering the insulating qualities of the switch. A convenient simple and eective manner of retaining the stationary insulating supporting member on the frame is also disclosed.

The entire switch is provided with an interlocking means whereby a new switch setting releases previous switch settings. This interlocking means is more fully described and claimed in the copending application of Mastney and Sus- 5 sin, Serial No. 180,742, filed December 20, 1937. However, in this particular construction, certain improvements have been made with regard to mechanical sturdiness.

An important feature of this invention resides 10 in the construction ofthe rigid contact. By virtue of such construction, a large number of switch combinations is possible since the rigid contact is adapted to be separated into small sections which may be insulated or not as desired from the rest of the blank. Thus by using the same prefabricated parts, and by merely controlling the arrangement of the spring contacts and arranging the separation of the rigid contact along any desired line, it is possible to obtain a go large number of possible switch' combinations. 'I'his is of great importance particularly for use in the manufacture of radios since each manufacturer of a radio has different circuits which are to be controlled. With the construction 25 hereinafter described, it is possible to fill orders for either a large or small number of switches. In either case the tooling is the same.

` Referring to the drawings, Fig. 1 shows a plan view .of a switch with parts broken away. Fig. 2 30 is a section on line 2-2 of Fig. l. Fig. 2a is a detail of a catch adapted to be attached to any one or more of the push rods shown in Fig. 2. Fig. 3 is a section on line 3--3 of Fig. l. Fig. 3a is a detail on line 3a--3a of Fig. 3. Fig. 4 is a 35 modined construction to be used and represents the portion of the' switch corresponding to the section line 3--3 of Fig. l. Fig. 4a is a detail on laf-4a. of Fig. 4. Fig. 4b is a detail showing how the insulating panel is to be fastened in position. 4p Fig. 5 is a section on line 5 5 of Fig. 1. Fig. 5a is a detail on line Suf-5a of Fig. 5. Fig. 6 is a section on line 8-6 of Fig. 1. Fig. 6a is a sectionaldetall on line Sa-Sa of Fig. 6. Fig. 'I is a detailof a rigid contact member. Fig. 8 is a 45 section on line 8-8 of Fig. 7. Fig. 8a is a detail on line Sel-8a of- Fig. 7. And Figs. 9 to 1l inelusive are details of various forms of spring contacts. f

Referring to Fig. 1, a metal or other suitable frame is shown comprising a top channel member Ill and a bottom channel member I I in spaced parallel relation. As shown in Fig. 2, channel members l0 and Il have the side edges in turned toward each other to form a generally U-shaped Fig. 6 to form a general U section with sides I4 and I8 bent outwardly parallel to the base portion I8 and I1 of each member. The side members I2 and I3 may be Joined to channels I8 and II in any suitable manner, such as, for example,`

by bolts or rivets as shown at one end of Fig. l, these passing through suitably shaped ends of the side members bent fiat against the channels I8 and I I.

Midway between side members I2 and |3 there may be disposed an intermediate supporting plate 28 of suitable material as metal shown in Fig. 3. This plate 28 is provided with a pair of projections 2I and 22 adapted to pass vthrough suitable registering slots in channel members I8 and II respectively and then to be staked to maintain the same lin position. It is understood, of course, that as many intermediate plates 28 may be provided as may be deemed necessary or may be omitted entirely. As shown in detail in Fig. 3, intermediate plate 28 is provided with a series of apertures 23 placed at regular intervals along side edge 24 thereof. It is understood, of course, that plate 28 is symmetrical in having a companion edge to edge 24 since both sides of the switch are similar. One portion of plate 28 here shown as a portion adjacent channel I8 is provided with a claw 28 which is adapted to engage one edge of a stationary supporting member 21 to be described in greater detail later.

As shown in Fig. 3, supporting plate 21 is substantially wider than intermediate plate 28 and in order to provide adequate support for the member an extension member 28 is provided. This extension member 28 is a fiat strip of metal having a finger 28 which is adapted to engage any one of apertures 23 in plate 20. This extension strip 28 has a series of apertures 23 which register with certain of apertures 23 in plate 28 when finger 28 engages an aperture 23. Extension 28 is provided with a second point of support to plate 28 at any one of the registering' apertures by means of an eyelet 38. Extension 28 has its free end provided with a claw 3| as clearly shown in Fig. 3. Claws 28 and 3| are adapted to engage the opposite edges of supporting member 21.

Prior to assembly, claw 28 is bent sideways as shown in Fig. 3a to permit supporting member 21 to rest upon a supporting ledge 32 on plate 28. Likewise, claw 3| is straight as, for example, shown in Fig. 4b to permit supporting member 21 to rest on ledge 33. After the supporting member 21 is disposed in position as shown in Fig. 3, claw 28 is straightened over supporting member 21 and claw 3| is bent down over supporting member 21 to lock the same in place.

In Fig. 4, a modified intermediate plate 28 is shown which`is generally similar to plate 28 of Fig. 3. Here the supporting member 21' is narrow enough .to obviate the necessity for an extension member such as shown in Fig. 3. In Fig. 4, the claw 3|. engages one edge of supporting member 21. The otheredge of insulating member 21' is supported in a modified form by the claws 28' and 32 shown in Fig. 4a. This permits member 21' to be higher upon the switch and makes possible the disposition of extra contacts. As clearly indicated in Fig. 4 and 4a, the plate 28 has its tip bmt around to parallel the edge of member 21. Claw 32 functions as a supporting ledge and claw 28', which is ordinarily in the position shown in Fig. 4a is thereafter bent over to lock supporting member 21' in position.

Supporting member 21, preferably of rigid insulation, extends throughout the extent of the frame and is adapted to be supported itself at the end members I2 and I 3. This is accomplished by the provision of lugs 38 and 38 extending through suitable apertures in supporting member 21. As shown in Fig. l, supporting member 21 is provided with a series of rectangular apertures 3l uniformly spaced and any successive two of which are adapted to be engaged by lugs 38 and 38. Apertures 31 are so spaced with reference to lugs 38 and 38 as to provide some play of member 21 in the direction of the length of these apertures, namely transverse to the entire supporting member 21 as shown in Fig. 1, but are adapted to fit lugs 38 and 38 rather snugly as regards movement transversely to the lugs. As shown in Fig. 5a, supporting member 21 is disposed so that lug 38 projects up through an aperture 31. The lugs 38 and 38 are so shaped that when member 21 is forced down iirst over lug 38 and then over lug 38, the curved rear edges of the lugs tend to move the member to engage as shown in Fig. 5. There a clearance in front of lug 38 and a clearancein the rear of lug 38 is shown. Lug 38, which is initially straight, is then twisted as shown in Fig. 5a to dispose it in locking position.

Supporting member 21 is provided with a plurality of series of apertures. Inasmuch as tle entire mechanism is merely a duplication of certain switch sections, it is only necessary to consider a portion of the entire mechanism in detail. Thus, for example, referring to the section or portion of the mechanism shown in Figs. 1 and 6, it will be seen that supporting member 21 and its companion member |21 is provided with a series of round apertures 48 and 4| spaced from each other and disposed transversely across the supporting member. Corresponding to each aperture 48 and 4| of the series is a companion series 42 and 43, respectively, of rectangular apertures.

The circular apertures, 48 or 4| or both, may have applied thereto a spring contact such as shown in Fig. 9 or 10. Thus, referring in detail t0 these contacts shown in Figs. 9 and 10, amounting portion 48 is shown of a doubled thickness of metal having a pair of oppositely bent spring Jaws 48 and 41. These spring jaws have their extreme edges 48 and 48 ared outwardly. Cutouts 88 may be provided in the metal to improve the resiliency thereof. A connecting portion 8| extends upwardly from mounting portion 48 at right angles thereto and is provided with an aperture 82 into which a suitable wire may be threaded and soldered. As clearly shown in'Fig. 9, the contact making portion of the clip comprises the two jaws 48 and 41 and this is bent down from mounting portion 48. The only difference between the clip shown in Figs. 9 and 10 is in the connecting portion. In Fig. 10 the connecting portion 8| is extended to provide a greater length.

As clearly shown in Fig. 6, a spring contact slip may be disposed at any one or more of the round apertures 48 or 4I by having the mounting portion 48 thereof retained against supporting member 21 by means of an eyelet 83. The mounting portion 48 is disposed in the outer surface 84 of supporting member 21 and has the contacting portion thereof extend down through the corresponding slot 42 or 43. Jaw 46 is preferably bent down at right angles to mounting portion 45 and with companion jaw 41 extends down through slot 42 and has sumcient room so that the jaws may open for contact making.

As shown in Fig. 6 the two rows of circular apertures 40 and 4| for mounting4 the spring contacts are spaced closely together in, comparison to the physical dimensions of the contact members themselves. The fact that the' spring jaws extend down through the corresponding rectangular slots 42 permits the spring Jaws of one contact to clear the connecting part of a neighboring spring contact. In that way the series of mounting apertures 40 and 4| may be disposed rather closely. It is understood, oi'

' course, that the precise arrangement of spring tacts proper.

contacts depends upon the number of circuits to b e controlled and the manner in which the control is to be exercised.,

In Fig. 1 1 a modified form of spring contact is shown wherein the mounting portion 45' is provided with' two separate contacting portions. each having 'jaws 46, 46' and 41, 41'. This type of contact may be used in place where interconnected spring contacts are desired from one series of rectangular apertures such as 42 to a neighboring series which may be either 43 or into another section of the entire switch mechanism. It is understood, of course, that two separate spring contacts such as shown in Fig. 9 or 10 may be mounted in a common aperture in backto-back relationship, but the modied contact shown in Fig. 11 is preferred where electrically necessary, since a neater and more compact construction results. It is understood, of course, that the connecting portion 5| of the ycontact shown in Fig. 11 may be short or long as desired.

Thus, through the series of rectangular apertures 42 or 43 an aligned row of spring contact jaws extends transversely of supporting .member 21.

Disposed within the switch structure shown in Fig. 1 are suitable movable members having movable contacts. Thus cooperating with supporting member 21 is a movable supporting member 60. As clearly understood, each section of the entire switch has duplicate members 60 and |60. This member 60, which is preferably of rigid insulating material has a face 6| and may ptreferably assume the form of a ilat elongated s rip.

Carried by a movable member 60 is a rigid contact blank which may be divided into as many unit sections as desired and which is shown in Fig. '7. This rigid contact comprises a fiat body portion 62 with upstanding side portions 63 and 64, the latter two of which form the rigid con- At spaced intervals, tabs 65 extend downwardly fromthe edge of body 62 away from contact parts 63 and 64. As shown in Fig. 8, the blank itself at the tabs has an H section whereas elsewhere the blank has a U section.

The entire blank may be considered as made up of a large number of unit portions with a longitudinal axis as shown in dotted lines and transverse axes as shown. These axes form the boundaries of adjacent unit sections. In order to remove excess metal from the blank and enable the blank to be cut up easily into unit or other sections as well as reduce electrical capacitance, the body portion 62 is provided with a number of apertures 61 whose centers are disposed at the intersections of the transverse and longitudinal axes. Thereafter various portions of the metal may be cut out to isolate any one or more unit sections. Thus, as shown in Fig. 7, a longitudinal strip may be cut out at 68 to separate the contacts in relation to the longitudinal axis of the blank. It is also possible to vcut out metal at 66 or 10 to isolate unit sections with regard to the transverse axes. It will be noted that the cut outs at 69 and 1D differ with respect to their extent and this is due to the spacing and proximity of the spring contacts and the desired action.

The rigid contact blanks are maintained on supporting member 60 by tapered vtabs 65 threaded through suitable apertures 1| (Fig. 1) which may be provided at uniformly spaced intervals. These tabs are bent along the lower surface of member 60 and retain the contact section rigidly in position. It is understood, of course, that in comparison to the spring contacts shown in Figs. 9 and l0 the contact portions 63 and 64 are heavy and relatively unyield- As is clearly evident in Fig. 6, the springr contact jaws oi' the clips extend downwardly through the rectangular apertures 42 or 43 toward the opposing face 6| of movable member 60. Likewise. rigid contacts 63 and 64 have their free edges 12 and 13 extend toward the opposing surface 15 of supporting member 21. Movable member 60 is supported, as will be later described, in a manner to provide play except with respect to the .length thereof. It is clear, therefore, that if movable member 60 were rocked or moved nearer to supporting member 21, that there would be danger of the spring jaws of the contact clips being injured. Inasmuch as it is important to prevent these jaws from being bent beyond their elastic limits, theirA protection is of great importance. This protection is accompllshed by providing a clearance, shown. as b in Fig, 6 between the inside surface 15 of member 21 and the free edges 12 and 13 of the rigid contacts, small` in comparison to the clearance a shown between the free edges 48 and 49 of the spring jaws and the body of the rigid contact blank 62. Naturally, vwhere the rigid contact material is removed, as might be the case under certain conditions, the clearance a is greater by the thickness of the metal so that in general, the clearance between the extreme edges of the spring contact jaws and the face 6| which opposes these edges is at all times larger than clearance b. Hence in the event of any rocking or movement of member 60, the rigid edges 12 and 13 which should always be longer than rectangular apertures 42 or 43, will strike against the bottom face 15 and limit the play. Thus, while the switch section is provided with normal clearances, nevertheless, considerable play is permissible without endangering the spring contacts. It should be noted that the amount of play b not only prevents the spring contact jaws from striking supporting member 60, but also acts to limit the opening of each pair of jaws 46 and 41 due to any movement of each rigid contact 12 or 13 out of its normal plane.

Asshown in Fig. 6, the general switch structure is provided with supporting members 21 and |21 and each of these supporting members has relatively movable members 60 and |60 respectively. As shown in Fig. 6, movable member |60 has rigid contacts along both sides thereof, although only one series of spring contacts is provided. The idle rigid contact serves as a bearing member to limit play.

'I'he two movable members 88 and |88 are y mounted on a plunger 88 which is shown in greater detail in Fig. 2. This plunger may be of any shape, but is here shown as being of at metal stock provided with a pair of large lugs 8| and 82 on opposite sides thereof and a series of small ears 88 and 84 on opposite sides thereof. Lug 8| projects through a suitable aperture 88 (see Fig. 1) in movable member 88. The ears 88 of the plunger are preferably co-planar and function as points of support for said movable member 88. As shown in Fig. l, aperture 88 is somewhat greater than lug 8| with regard to the thickness of the metal of lug 8| and thus permits some side movement of member 88 with respect to the plunger. As seen in Fig. 1, this play would be up and down and would be perpendicular to the length of the plunger. By tapering lug 8| as shown in Fig. 2, play in the direction of the length of the plunger 88 is eliminated. By this form of mounting, the entire movable member 88, together with its rigid contacts, is permitted to adjust itself to the requirements of the various spring contacts within wide limits and the only coupling with substantially no play at all is along the length of the plunger which is the direction of motion of the movable member during switching operation.

Similarly, movable member |88 is supported by ears 84 and lug 82.

Plunger 88 is provided with an handle or actuating portion 88 which projects through a suitable slot 88 in channel member I8. Portion 88 may have its free end provided with a push button 81. In order to quiet the operation of the plunger rod, a rubber or felt washer 88 may be disposed on the inside surface of channel member I8 and separate this channel member from the shoulders 3of plunger 88. 'Ihe central portion of plunger 88 is provided with a rectangular aperture 88, which is preferably disposed midway between the opposite sides of the rod although this is not essential. In line with aperture 88 along the longitudinal axis of the plunger is an elongated cut out 8i whose portion 82, adjacent to cut out 88, is widened to approximate the dimension of cut out 88.

Further down the plunger a large cut out reglon 84 is provided, with such a shape as to provide projections 85 and 88 opposing each other along the longitudinal axis of the rod. As is evident in Fig. 2, projection 88 is substantially longer than 88 and this projection 88 is adapted to extend through a suitable slot in channel member II. Disposed around opposite projections 88 and 86 is a coil spring 88 which obviously tends to maintain the plunger so that the button 81 is at its highest position away from channel I8. If desired. a rubber or felt washer 88 (see Fig. 1) may be disposed around projection 88 and against the outside of channel II.

The various plungers 88 of each portion of the switch are all parallel to each other and normally tend to assume positions where the various cut outs register with each other. In order to provide an interlocking action a ladder bar |88 is provided. This bar as shown in Fig. 1 has a straight bottom edge |8I and a generally serrated top edge |82. For each switch action one serration is provided and this in general assumes the form of a long sloping edge |88, terminating in a tip |84 and then rounded oif to form a nose |88 which finally ends in a recessed part I 88. The recessed part |88 goes into a at portion |81 and this flat portion |81 then is extended to form another inclined portion |88 of a new serration.

One end II8 oi ladder bar |88 has the full width of the bar and is adapted to play in end member I8. This member I8 is provided at a suitable interior portion thereof with a slot III whose intermediate portion II2 is widened out beyond the normal requirements of ladder bar |88. In this way, merely the ends of slot III actually operate as bearing portion so that friction is reduced. 'I'he intermediate platesl such as 28 and 28' are provided with cut outs i|8 and II8' respectively. substantially larger than the cross section of ladder bar |88 so that no friction is created.

The other end of ladder bar |88 shown in Fig. 8a is provided with a stop III adapted to bear against the inside surface of side plate I2 in its extreme position. The free end of the ladder bar |88 is reduced at II8 to a width substantially less than the rst end II8. This reduced end II8 is shaped as shown in Fig. 6a to provide two tapering sides II1 and II8 to terminate in an enlarged head portion II8. Reduced portion H8, as pointed out before, extends beyond plate I2 and around this reduced portion a coil spring |28 is disposed. By virtue of the enlarged head |I8, spring |28 may be locked in place and normally tends to keep the ladder bar in the position shown in Fig. 1. In this position, nose |88 of each serration is adapted to extend within the plane. of the corresponding plunger 88. Thus, upon any plunger being depressed, the strip of metal 88 acts against nose I 88 of the ladder bar and forces said bar lengthwise against its normal biased position. As shown in Fig. l, this would be a leftward movement of ladder bar |88. Upon the completion of the downward movement of any one plunger, the corresponding nose |88 will be opposite aperture 88 of the plunger and permit the latter plunger to attain its normal position. In that position, nose |85 of the ladder bar is disposed in aperture 88 and locks the corresponding plunger 88 in its dow-n position and against the spring 88. At the same time, any other plungers which have previously been in their down position are released during the oif normal position of the ladder bar and permitted to assume their normal up position. As pointed out in the copending application previously referred to, the nose |88 for each serration is so shaped that upon extreme downward movement of any plunger such as, for example, |88 in Fig. l, the ladder bar is also released.

It is understood, of course, that the movable portions 88 and |88 and the cooperating stationary portions 21 and |21 may be made as wide as desired so that any number of contacts for each switch section may be disposed. The length, of course. may be adjusted so that any number of switch sections may be provided.

As shown in the switch of Fig. 1, one of the plungers |8I is adapted to control a snap switch which, in the case of a radio, may be the main switch for turning the set on or oif. In this case, the plunger which is the same as shown in Fig. 2

and may be referred to as 88, has a catch |82 v shown in Fig. 2a. This ismerely a piece of metal having apertures |88 adapted to register with apertures |84 normally provided in the plunger blank. Suitable rivets may be disposed in the registering apertures to support catch |82 on whichever side of the plunger desired. Thus.

catch |82 having a finger |88 as shown in Fig. 6

aromas extends upwardly through a suitable slot |88 in member 21. This slot |86 is long enough to accommodate the travel of finger |85 throughout the length of movement of plunger I 8|. Finger |85 is adapted to operate between the two portions |8'| and |88 of a pivoted member |89. Member |89 may be used to operate any suitable snap switch mechanism.

What is claimed is:

1. An electric switch comprising a base, a pair of rigid contact supporting members having spaced opposing surfaces adapted to be normally in fixed parallel planes, means for supporting said members on said base to maintain said surfaces and to be movable with respect to yeach other in a certain direction for switching purposes, said supporting means including means for retaining such members rigidly along the line of switching motion but providing relative play in other directions between said members thus tending to disturb the normal parallel relationship between said opposing surfaces, at least one rigid contact carried by one of said members and extending toward the opposing member surface and having active sides for contacting purposes and terminating in a free bearing edge lying in the line of switching motion and being sufficiently long to have at least a portion thereof free to engage the opposing member surfacein all switch positions and having a normal clearance between said bearing edge and opposed member surface serving to define a limit to saidplay, and at least one cooperating spring contact carried by the other member and having its active portion extending toward the opposing member surface with a clearance therebetween substantially greater than said first clearance, said spring contact normally engaging at least one side of said rigid contact whereby distortion of said spring contact due to play is kept within safe limits.

2. An electric switch comprising a base, a pair of rigid contact carrying members having flat faces, means for mounting said members with the flat faces in opposed relation on said base to provide relative movement between said memmounting 'said spring and rigid contacts on each of said members respectively to extend toward the opposing member, said rigid contact having a normal clearance between its bearing edge and the opposed member face, the spring contact having a normal clearance between it and the opposed member face which is substantially larger than the first clearance, one of said mounting means providing play between cooperating contacts in directions other thanthe line of switching motion, said rigid contacts being long enough along the line of switching motion so that in all switching positions said rigid contact bearing edge together with the opposed member face serve to limit play and protectthe spring contact against damage.

3. The switch of claim 2 wherein the mounting means for one of said contact carrying members provides the play, said mounting means supporting said member along the line of switching motion.

4. The switch of claim 2 wherein the mountrigid contact carrying members having fiat faces.

means for mounting said members with said faces in opposed relation on said base to Vprovide relative movement between said members along a straight line for switching purposes, onel of said mounting means providing play' between said members in directions other than the line of switching motion, at least two rigid contacts each having a straight blade-like portion adapted to extend along the line of switching motion and having active contacting portions at the sides thereof and having straight bearing edges, said rigid contacts being mounted inparallel planes, at least one spring contact for each of said rigid contacts, means for mounting said spring contact and rigid contact on each of said members respectively to extend toward the opposing member, all spring contacts being mounted on one member and all rigid contacts being mounted on another member, said rigid contacts having a normal clearance between their bearing edges and the opposed member face, the spring contacts having a clearance between them and the opposed member face which is substantially larger than the first-named clearance, each of said rigid contacts being long enough along the line of switching motion so that in allswitch positions said rigid contact bearing edge together with the opposed member fac'e function to limit play and protect the spring contacts against damage.

6. The switch of claim 5 wherein the mounting means for the rigid contact carrying member provides the play.

7. The switch of claim 2 wherein the spring contact carrying member is apertured with the spring contacts mounted on a side of the member remote from the opposing member with the contact bearing portion of the spring contact extending through said aperture toward the opposing member.

8. The switch of claim 5 wherein the rigid contact carrying member facehas a generally U-shaped blank disposed thereon, the sides of the U forming the rigid blade-like contacts with each rigid contact divided into unit sections each section having a fastening means for retaining said rigid contact on said contact carrying member and wherein the connecting portion between opposed rigid contacts is adapted to be cut up along various lines so that each unit rigid contact section may be connected to or disconnected from opposite or adjacent contact sections.

9. The switch of claim 2 wherein the spring contact includes a pair. of spring jaws adapted to enclose the rigid contact on opposite sides with the spring contact mounted on its carrying member on a side remote from the rigid contact and extends through an aperture in said carrying member toward the opposing member face.

l0. 'I'he switch of claim 5 wherein the contact carrying members are fiat strips each having a tends through an aperture with each spring contact having a pair of spring jaws adapted to enclose the rigid contact on opposite sides thereof and wherein the rigid contact is divided into unit sections having a fastening means engaging an aperture in its carrying member.

11'. An electric switch comprising a base, a plunger mounted on said base and movable back and forth along a straight line. a movable con-- carrying members having opposed at faces, a

rigid contact carried by said movable ycontact carrying member, said rigid contact having a generally blade-like shape extending in the line of switching motion and extending toward the opposing member face and terminating in a straight bearing edge having a predetermined normal clearance therefrom, said rigid contact extending from said member along a line offset from the mounting line oi.' said movable member, spring contacts carried/by said stationary member and extending toward said movable member and having active portions adapted to engage the side of said rigid contact and having a clearance from said movable carrying member substantially greater than the first clearance whereby when said movable member tilts on its mounting the bearing edge of said rigid contact will engage the opposing member surface first to limit the play and to protect the spring contact against damage.

12. The switch of claim 11 wherein the movable member has a pair of rigid contacts mounted thereon on opposite sides of the line of support of said member each of said contacts extending toward the opposing member surface along parallel planes with spring contacts for each of the rigid contacts.

13. In an electric switch, a front and rear elongated channel member disposed in parallel relationship and having transverse registering slots therethrough forming a series of pairs of slots, a straight fiat plunger for each pair of slots, said plunger having a handle portion extending through the front member slot, said plunger having an enlarged body portion extending from the front member to the rear member with a cut out near the end thereof through which the rear member is threaded, said plungerY having an inwardly extending tongue in the rear slot extending from the outside of the member to the space between said members, and a spring coiled around said tongue for biasing said plunger.

KENNEIH C. ALLISON. 

